... cancellation 4.Big round PTT Power-Time professional Helmet Headset/Fireman Headset for two way radio Model ... 119D 1.Durable and Portable,Specially for the Helmet,unique design wearing on shoulders and arms,make ... can setup in the existing and almost all helmet without any tools help.2.To provide ... closed helmet,face cover or mask,and using by fireman,Emergency and chemical Denfense.4.Earphone with ...